code: def test_raises_error_if_evaluating_single_variable_and_threshold_is_None(
      df_test,
  ):
      X, y = df_test
  
      sel = SelectBySingleFeaturePerformance(
          RandomForestClassifier(random_state=1),
          variables=["var_1"],
          threshold=None,
      )
  
      with pytest.raises(ValueError):
          sel.fit(X, y)
  
file_path: feature_engine/tests/test_selection/test_single_feature_performance_selection.py
imports: import warnings
  import numpy
  import pandas
  import pytest
  from sklearn.ensemble import RandomForestClassifier
  from sklearn.linear_model import LinearRegression
  from sklearn.tree import DecisionTreeRegressor
  from feature_engine.selection import SelectBySingleFeaturePerformance
label_desc: Use image node_id 9 for calling a global function with example usage: test_raises_error_if_evaluating_single_variable_and_threshold_is_None(df_test) without return types